Converting un known audio format

Question

I used my AWA mp3 player to record a meeting, but cannot listen to the file on my computer. the file does not have a file extension and is not recognised by any audio converters. can you please tell me what format is used and how to convert it to MP3 or any other recognisable/ known format to be played by any of the known media players

My PD-6070 records in .WAV [dot WAV].  Can I change it to record in MP3?

I can change the recordings by importing them to iTunes, but I want to know how to change the way the PD-6070 player records microphone input.